alternator not putting out a charge even though its good

zachpierce

New Member
Jan 3, 2010
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ok i have checked it all around the wire from the alternator. i decided to check the wire that goes to the alternator to the selniod(black with orange strip) at both spots while i had it off the selniod and both spots (at the end of the wire and the begaining of the wire from the alternator did not put out a reading. while it was hooked up to the selniod it read the same as the battry did which was 11.7 so i know the wire is good. what could it be beside the new alternator? autozone says its good. hmmm its to late to take it back again. please help. did i maybe, have a wire ran somewhere wrong? i had to swap the dash and main hardness durning the engine swap. and where and what is the diode?

ok i change the big wire on the battert to the selniod today. that was my first guess. i have a question would my alternator stop putting out a charge all together if i unhook my evg from the throttle body? i did so today as i was putting the new alternator on. i put a block plate on and just left the plus un done so i could get ride of all that emmision stuff. i decided to pull the wire that goes to the battery from the alternator and check it with my voltage meter while the car was running and its not putting out any volts. but reads what the battery does while running when its hooked up to the selniod. which is 11.7 are lower. please help if you can. im so ready to drive this car. been working on it for 3 months straight with the swap i did.

its a new aternator and i went and had it checked tonight at autozone. they say its good but even after i re-hooked up the evg on the thottle body it still is not putting out a charge. this bs is killing me. i have worked so hard on the whole swap. the old alternator was killed by an elec. fan i put on the car. so of course i have taken it back off. they checked that alternator and it was bad thats why i have the new 1 now. it has to be a wire some where not letting the alternator give off a charge. i know its grounded right and my battery is good. i know this cuz of all the test i did with the voltage tester. what could it be?

fromer owner of 1968 mustang, own 1990 lx 5.0,1989 lx, & a 1995 v6 . the one im swapping is the 1989 it has trick flow intake, mac shorty pipes, h-pipe, flowmasters, pro 5.0 shifter, t-5(5yrs. old), all msd ing. mds spark plug wires 8.5, no smog, elec. fan, rebuit engine, 3.73 gears, underdrive pulleys.
 
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The only thing I can guess from what ive gathered from all that is...
1. Check continuity from wires going to and fro, seein how you had a mishap with your fan you mentioned.
2.If you start your car and unhook the battery and it dies the alternator is bad or not hooked up right or wire problems.
3.Battery starts the car, Alternator keeps it running. Thats it. Still pulls little charge from battery.
Autozone has failed me many times with sayin things are good. Bottom line I would do the startin the car and unhookin the battery to see if the alternator is even working or sending out. If not, theres a fault in the wiring somewhere somehow.
 
couldnt i check the alternator like i did by un-hooking the wire that goes to the selniod and testing it then? i did that and not volts on that wire from the alternator. thats what i am asking is there a wire that could be ran wrong or bad that would stop my alternator from working?
 
An alternator can function properly and still not put out a charge, if you use a voltmeter at your batt + and - check voltage while car is running if its not putting out 13-14.5 volts and your wiring is good its probably the alt. The auto parts stores test equipment does not always check output voltage.
 
ok i had the alternator check on at a place that shows the voltage that it is putting out. it was at 14 volts or so. i came home and decided to pull off the alternator braket and grind away the spots that touch the block to make sure i have a grat ground. put it al back together and still same problem its not putting out any volts. everything else works on the car like starting. i drove it to work today (2miles away). i know it was running just off the battery but i need to use this car for work. i am wondering if there is a wire on the alternator plug that is hooked up wrong & not letting it kick on. can there be? i checked the plug(black with orange strip) itself and its good. i looked at a good diagram by tmoss and seems like there isn't a wire that could cause it not to put out a charge. please help if you can.
 
Make sure your not grounding out somewhere. With the car off and the positive unhooked see if you get a spark when you touch the positive. If there is its not grounding. Also make sure your wires goin to the solenode are hooked up on the right sides. And the battery wires are good and no corrosion.
 
when you pulled the dash out you broke a connection to the alternator...the small green wire on the alternator runs to the dash and completes the circuit...if you don't want to take the dash back out run that green wire to the ignition.
 
when you pulled the dash out you broke a connection to the alternator...the small green wire on the alternator runs to the dash and completes the circuit...if you don't want to take the dash back out run that green wire to the ignition.


No, do not run that green wire directly to the ignition switch. First, the green wire does not complete the circuit.. and second.. running that green wire directly to the ignition switch is asking for trouble. Here is why.. The green wire comes from the alternator and connects to the dash "AMP / Alt " warning indicator lamp, then from there it connects to the ignition switch key on terminal. Bypassing the warning bulb and directly connecting to switch may result in overheated wires, fire, or possibly a damaged regulator. If yo're going to connect that wire, make sure you run it to the warning indicator.

As for your no charge issue, you need to check the yellow wire coming from the alternator. That is for the voltage regulator. It will come around and connect to a fuse link, and then to the solenoid. If that wire is disconnected or the fuse link is bad, then your alternator will not output a voltage. If the wire is connected, first disconnected battery with car off and then disconnect the side at the solenoid. Using your meter, connect to both ends of wire and test for continuity. I have found that fuse link tends to burn out easily, especially with older wiring. The culprit is usually overheated fuel pump wires grounding out, or ... possibly in your case, the electric cooling fan. I had this problem on an 89 GT I once owned. If I were you, I would upgrade that alternator to ..say.. one of those PA Performance alts. The 130 amp upgrade. Plus upgrade the alt wiring. If you are using a stock 65 or 75 Amp alternator, that just wont cut it. Especially at idle, that electric fan will fry that alt in no time. Just like it did before.